Color image forming method using silver halide, reducing agent, polymerizable compound and colorant

ABSTRACT

The present invention provides 4 embodiments of a new image forming method. The image forming method uses a light-sensitive material and an image receiving material. The light-sensitive material comprises a support and a light-sensitive polymerizable layer provided thereon. The light-sensitive polymerizable layer contains silver halide, a reducing agent, an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer and a colorant. The image forming method comprises an exposing step, a developing step, a removing step, a transferring step and a repeating step. Some embodiments of the method further contain a laminating step. The present invention is characterized in that a multicolor image is formed on an image receiving material by the repeating step.

FIELD OF THE INVENTION

The present invention relates to an image forming method using a polymerization reaction initiated by silver halide. The invention also relates to an image forming method using a light-sensitive material which can be imaged with a scanning light such as a laser bean. The invention further relates to an image forming method which is advantageously used for forming a color proof.

BACKGROUND OF THE INVENTION

As the computer technology has recently been developed, a technical innovation is greatly introduced in printing. The field of color printing is now digitized by using a computer system named as CEPS (Color Electronic Preptess System). The CEPS digitizes the printing data of a color image and the data of all the preptess process down to stripping. Further, the newest system directly outputs the digitized printing data to a presensitized printing plate of a high sensitivity to prepare a printing plate without use of a conventional lith film. The technical innovation in the printing field makes the lith film unnecessary.

Before running on, a proofread is necessary to inspect the finished quality of printing. The proofing systems include a pressproof and an analogue offpress proof. The pressproof comprises preparing a printing plate for a proof sheet and printing an image using a proof press. The analogue offpress proof employs an image forming system different from the printing system. The offpress proof system comprises uniformly exposing to light a light-sensitive material through a lith film. The light-sensitive material contains a photopolymer, and the light source usually is ultraviolet. These two proofing systems are based on the premise that the printing system uses a lith film. The proof sheet itself is prepared from the image on the lith film (cf., M. H. Bruno, Principle of Color Proofing).

As is mentioned above, the conventional proofing systems are based on use of the lith film. Now, it is an important problem how to inspect the printing quality when the technical innovation in the printing field makes the lith film unnecessary. Therefore, the newest printing system requires a proof system of preparing a proof sheet directly from digital image data without use of the lith film. The required proof system is named as DDCP (Digital Direct Color Proof). With respect to the DDCP, several systems have been proposed, and some of them are practically used.

The DDCP systems employ an electrophotography and a thermal transfer recording system, which are completely different from the conventional analogue offpress proof using a photopolymer. The proofing qualities of DDCP (such as resolving power, color tone, gradation, reproducibility of half tone, analogy to printing and stable reproducibility of the image) are insufficient compared with the conventional systems. The image qualities of the direct output from a digital image are not satisfied. Therefore, an improved proofing method which can directly output the digital image is required to obtain a color proof of high quality.

Japanese Patent Publication No. 48(1973)-31323, Japanese Patent Provisional Publications No. 59(1984)-97140, No. 62(1987)-267736, No. 2(1990)-244151 and U.S. Pat. No. 3,770,438 disclose an analogue offpress proof using a conventional photopolymer. If the digital image data can directly be recorded on the offpress proof using the photopolymer, the proofing qualities are probably satisfactory. However, the digital image data should be recorded on a light-sensitive material for proof by a scanning exposure using a specific light source such as a laser bean. Therefore, the light-sensitive material should have a high sensitivity to the wave length of the scanning light. The conventional light-sensitive material using a photopolymer does not have such a high sensitivity. Further, it is particularly difficult to sensitize the photopolymer to a laser beam of a long wave such as a He-Ne laser and a semiconductor laser. The photopolymer merely has a sensitivity to a laser beam of a short wave. Accordingly, the conventional analogue offpress proof is not available in the DDCP systems.

In conclusion, the offpress proof using a photopolymer cannot directly record the digital image data, since the photopolymer does not have a high sensitivity to the wave length of the scanning light (particularly a laser beam of a long wave). On the other hand, the proofing qualities of the conventional DDCP systems (using an electrophotography or a thermal transfer recording system) are insufficient with respect to resolving power, reproducibitity of half tone or stable reproducibility of color. Therefore, a new DDCP method is required to record a color proof of high quality with a high sensitivity to the wave length of a scanning light.

By the way, Japanese Patent Provisional Publications No. 61(1986)-69062 and No. 61(1986)-73145 (the contents of these two publications are described in U.S. Pat. No. 4,629,676 and European Patent Provisional Publication No. 0174634A) discloses an image forming method using a light-sensitive material which contains silver halide, a reducing agent and a polymerizable compound. The method comprises the steps of imagewise exposing to light the light-sensitive material, and heating the material to develop the silver and to harden imagewise the polymerizable compound. Thus a polymer image is formed on the light-sensitive material. In a representative embodiment of the method, the developed light-sensitive material (containing a colorant) is pressed on an image receiving material to transfer the colorant with the unpolymerized polymerizable compound to the image receiving material. Thus a color image is formed on the image receiving material. In the case that a multi-color image is formed on the image receiving material, the light-sensitive material should contain two or more kinds of microcapsules (or packet emulsions) each containing a colorant different from each other.

SUMMARY OF THE INVENTION

The present inventors paid attention to the image forming method using a polymerization reaction initiated by silver halide, and have tried to apply the method to formation of a color proof. However, the inventors note some problems when the image forming method itself is applied to the color proof.

For example, there are the following problems (1) to (4) where a multicolor image is formed by using two or more kinds of microcapsules each containing a colorant different from each other.

(1) Using the microcapsules, the resolving power of the light-sensitive material is limited to the size of the microcapsules.

(2) The microcapsules are ruptured by pressure to form an image. The resolving power is more degraded than the size of the microcapsules, since the contents of the microcapsules are spread by the pressure.

(3) The amount of the colorant contained in the microcapsule is severely limited. Accordingly, the maximum density of the image is low.

(4) The printed matter has overlap of color (ink). The method using microcapsules cannot reproduce the overlap.

An object of the present invention is to improve the image forming method using a polymerization reaction initiated by silver halide and to provide a method advantageously used for forming a color proof.

Another object of the invention is to provide an image forming method which can form a color proof directly from digital image data without use of a lith film.

A further object of the invention is to provide an image forming method which forms a color proof of a high quality by a scanning exposure with a laser beam, particularly a laser beam of a long wave.

A still further object of the invention is to provide an image forming method which can form a hardened image with a low exposure energy, whereby a color proof is made from the hardened image

The present invention provides an image forming method comprises the four embodiments. Each of the embodiments is a method which uses a light-sensitive material and an image receiving material. The light-sensitive material comprises a support and a light-sensitive polymerizable layer. The light-sensitive polymerizable layer contains silver halide, a reducing agent, an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer and a colorant.

The first embodiment comprises the steps of:

(1) imagewise exposing to light the light-sensitive polymerizable layer (hereinafter referred to as an exposing step);

(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (hereinafter referred to as a developing step);

(3) placing the light-sensitive material in contact with the image receiving material to transfer the unhardened area to the image receiving material whereby a color image is formed on the image receiving material (hereinafter referred to as a transferring step); and then

(4) repeating the steps (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (hereinafter referred to as a repeating step).

The second embodiment comprises the steps of:

(1) imagewise exposing to light the light-sensitive polymerizable layer (an exposing step);

(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (a developing step);

(3) placing the light-sensitive material in contact with the image receiving material to transfer the hardened area to the image receiving material whereby a color image is formed on the image receiving material (a transferring step); and then

(4) repeating the steps (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (a repeating step).

The third embodiment comprises the steps of:

(A) laminating the light-sensitive material on the image-receiving material (hereinafter referred to as a laminating step);

(1) imagewise exposing to light the light-sensitive polymerizable layer (an exposing step);

(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (a developing step);

(3) peeling the image receiving material from the light-sensitive material to transfer the unhardened area to the image receiving material whereby a color image is formed on the image receiving material (hereinafter referred to as a transferring step); and

(4) repeating the steps (A) and (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (a repeating step),

wherein the order is selected from:

(A)→(1)→(2)→(3)→(4); and

(1)→(A)→(2)→(3)→(4).

The fourth embodiment comprises the steps of:

(A) laminating the light-sensitive material on the image-receiving material (a laminating step);

(1) imagewise exposing to light the light-sensitive polymerizable layer (an exposing step);

(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (a developing step);

(3) peeling the image receiving material from the light-sensitive material to transfer the hardened area to the image receiving material whereby a color image is formed on the image receiving material (a transferring step); and

(4) repeating the steps (A) and (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (a repeating step),

wherein the order is selected from:

(A)→(1)→(2)→(3)→(4); and

(1)→(A)→(2)→(3)→(4).

In the four embodiments, the light-sensitive polymerizable layer preferably comprises a light-sensitive layer containing the silver halide and a polymerizable layer containing the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer and the colorant.

The reducing agent may be contained in the light-sensitive layer or/and the polymerizable layer. Further, the light-sensitive polymerizable layer may comprise a light-sensitive layer, a polymerizable layer and an image formation accelerating layer. The reducing agent may also be contained in the image formation accelerating layer. In the present specification, the light-sensitive polymerizable layer comprising two or more functional layers is referred to as "a complex light-sensitive polymerizable layer". A light-sensitive material having the complex light-sensitive polymerizable layer is referred to as "a multi-layered light-sensitive material". On the other hand, a light-sensitive material having a single light-sensitive polymerizable layer is referred to as "a single-layered light-sensitive material".

In the first and second embodiments, a polymerizable layer is provided on a support, and a light-sensitive layer is provided thereon. In the third and fourth embodiments, a light-sensitive layer is provided on a support, and a polymerizable layer is provided thereon.

When a multi-layered light-sensitive material is used in the first and second embodiments, the light-sensitive layer should be removed before the developing step and the transferring step. In the case that layers other than the light-sensitive layer and the polymerizable layer are provided on a support, a layer provided on or above the polymerizable layer should also be removed.

In the present invention, two or more steps can be conducted simultaneously provided that the above-defined order is not reversed. For example, the exposing step (1) can be conducted simultaneously with the developing step (2). A process conducting two or more steps simultaneously is included within the scopes of the present invention.

The image forming method is characterized in that the steps are repeated using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material. This method has the following advantages (1) to (4) compared with the previous method using microcapsules.

(1) Using the microcapsules, the resolving power of the light-sensitive material is limited to the size of the microcapsules. There is no such limitation on the method of the invention.

(2) The microcapsules are ruptured by pressure to form an image. The resolving power is more degraded than the size of the microcapsules, since the contents of the microcapsules are spread by the pressure. There is no such problem on the method of the invention.

(3) The amount of the colorant contained in the microcapsule is severely limited. On the other hand, a relatively large amount of the colorant can be contained in the light-sensitive material. Therefore, a high maximum density of an image can be obtained according to the present invention.

(4) The printed matter has overlap of color (ink). The method using microcapsules cannot reproduce the overlap. The method of the invention can reproduce the overlap by repeating the above-mentioned steps where the color of the colorant or toner corresponds to the color of the ink in the printed matter. Therefore, the present invention can form an excellent color proof having a color tone which is very similar to that of the printed matter.

Thus the problem of the image forming method using a polymerization reaction initiated by silver halide is solved by the present invention. This method now can be applied to formation of a color proof.

Therefore, a color proof can be formed directly from digital image data without use of a lith film. Further, a color proof of a high quality can be formed by a scanning exposure with a laser beam, particularly a laser beam of a long wave. Furthermore, a hardened image can be formed with a low exposure energy

Further, the following effects can be obtained by using the specific embodiments of the present invention.

1. In the second and fourth embodiments, the hardened area is transferred to the image receiving material. The hardened area is mechanically strong compared with the unhardened area. Therefore, the reproducibility of a minute image such as a half tone is improved in the second and fourth embodiment to form a clear image.

2. In the third and fourth embodiments of the invention, the light-sensitive material is laminated on the image-receiving material. These embodiments have an advantage of easy adjustment and easy operation with respect to the setting of an image.

3. In the multi-layered light-sensitive material having a light-sensitive layer and a polymerizable layer, silver halide does not influence on the color tone of the polymerizable layer.

Further, the components of the light-sensitive layer such as silver halides are not contained in the polymerizable layer. Therefore, the polymer image formed in the polymerizable layer has a high mechanical strength, since the polymerizable layer substantially consists of only the polymerizable compound or the cross-linkable polymer. A clear color image can be formed from the strong polymer image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view schematically illustrating a single-layered light-sensitive material used in the image forming method of the present invention.

FIG. 2 is a sectional view schematically illustrating another embodiment of a single-layered light-sensitive material used in the image forming method.

FIG. 3 is a sectional view schematically illustrating a multi-layered light-sensitive material used in the first and second embodiments of the image forming method.

FIG. 4 is a sectional view schematically illustrating a multi-layered light-sensitive material used in the third and fourth embodiments of the image forming method.

FIG. 5 is a sectional view schematically illustrating the exposing step of the first and second embodiments of the image forming method.

FIG. 6 is a sectional view schematically illustrating the developing step of the first and second embodiments of the image forming method.

FIG. 7 is a sectional view schematically illustrating the transferring step of the first embodiment of the image forming method.

FIG. 8 is a sectional view schematically illustrating the color image obtained by the repeating step of the first embodiment of the image forming method.

FIG. 9 is a sectional view schematically illustrating the laminating step of the third and fourth embodiments of the image forming method.

FIG. 10 is a sectional view schematically illustrating the exposing step of the third and fourth embodiments of the image forming method.

FIG. 11 is a sectional view schematically illustrating the developing step of the third and fourth embodiments of the image forming method.

FIG. 12 is a sectional view schematically illustrating the transferring step of the third embodiment of the image forming method.

DETAILED DESCRIPTION OF THE INVENTION

First, preferred embodiments of the present invention are described below.

(1) The light-sensitive polymerizable layer preferably comprises a light-sensitive layer containing the silver halide and a polymerizable layer containing the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer and a colorant.

(2) The light-sensitive material is preferably developed by heating. The heating temperature is preferably in the range of 70° to 200° C.

(3) The light-sensitive polymerizable layer preferably further contains a base or base precursor. With respect to the complex light-sensitive polymerizable layer, the base or base precursor can be contained in the light-sensitive layer or/and the polymerizable layer. The base precursor is preferred to the base. The base or base precursor may be contained in an image formation accelerating layer.

(4) The light-sensitive polymerizable layer may further contain a heat development accelerator. With respect to the complex light-sensitive polymerizable layer, the heat development accelerator is preferably contained in the polymerizable layer. The heat development accelerator may be contained in an image formation accelerating layer.

(5) In the case of a multi-layered light-sensitive material, the light-sensitive layer preferably contains a hydrophilic binder

(6) The light-sensitive polymerizable layer (the light-sensitive layer or the polymerizable layer of the multi-layered light-sensitive material) or the adhesive layer (of the third or fourth embodiment) may further contain a substance which absorbs the exposing light from the light source.

(7) The light-sensitive material may have a layer containing a substance which absorbs the exposing light from the light source on the side of the light-sensitive polymerizable layer.

(8) The light-sensitive material may have a layer containing a substance which absorbs the exposing light from the light source on the reverse side of the light-sensitive polymerizable layer (the back side of the support).

(9) The light-sensitive material may have a protective layer as the uppermost layer.

(10) The light-sensitive material may have an image formation accelerating layer which contains one selected from a reducing agent, a base, a base precursor and a heat development accelerator.

(11) After the image is formed on the image receiving material, the image may be further transferred to the secondary image receiving material.

Next, the layered structure of the (single-layered or multi-layered) light-sensitive material used in the image forming method of the present invention is described below referring to the drawings.

FIG. 1 is a sectional view schematically illustrating a single-layered light-sensitive material used in the image forming method of the present invention. A single light-sensitive polymerizable layer (12) is provided on a support (11). The light-sensitive polymerizable layer (12) contains silver halide (13), a reducing agent (14), an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer (15) and a colorant (16).

FIG. 2 is a sectional view schematically illustrating another embodiment of a single-layered light-sensitive material used in the image forming method. A single light-sensitive polymerizable layer (22) is provided on a support (21) in the same manner as in the embodiment shown in FIG. 1. However, a hydrophilic phase (27) containing silver halide (23) is separated from and finely dispersed in a hydrophobic phase containing the other components, namely a reducing agent (24), an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer (25) and a colorant (26).

As is shown in FIG. 2, a phase separation may be caused in the light-sensitive polymerizable layer. In other words, it is not necessary to form the light-sensitive polymerizable layer as a uniform layer.

FIG. 3 is a sectional view schematically illustrating a multi-layered light-sensitive material used in the first and second embodiments of the image forming method. A polymerizable layer (32) is provided on a support (31), and a light-sensitive layer (33) is provided on the polymerizable layer (32). The polymerizable layer (32) contains a reducing agent (34), an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer (35) and a colorant (36). The light-sensitive layer (33) contains silver halide (37).

The reducing agent can be contained in the light-sensitive layer (33) though the reducing agent (34) is contained in the polymerizable layer (32) of the light-sensitive material shown in FIG. 3. The reducing agent may be contained in both of the polymerizable layer and the light-sensitive layer in any ratio of the amount. Further, the reducing agent may be contained in an image formation accelerating layer.

FIG. 4 is a sectional view schematically illustrating a multi-layered light-sensitive material used in the third and fourth embodiments of the image forming method. A light-sensitive layer (42) is provided on a support (41), and a polymerizable layer (43) is provided on the light-sensitive layer (42). The light-sensitive layer (42) contains silver halide (44). The polymerizable layer (43) contains a reducing agent (45), an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer (46) and a colorant (47).

The reducing agent can be contained in the light-sensitive layer (42) though the reducing agent (45) is contained in the polymerizable layer (43) of the light-sensitive material shown in FIG. 4.. The reducing agent may be contained in both of the polymerizable layer and the light-sensitive layer in any ratio of the amount. Further, the reducing agent may be contained in an image formation accelerating layer.

The above-described layered structures are examples of the light-sensitive material. The present invention is not limited to the examples.

For example, optional layers such as an undercoating layer, an overcoating layer (e.g., a protective layer or a cover sheet), an intermediate layer and a backing layer can be provided on the light-sensitive material. The undercoating layer is provided on the support. The overcoating layer is provided as the uppermost layer. The intermediate layer is provided between the functional layers. The backing layer is provided on the reverse side of the light-sensitive polymerizable layer (the back side of the support).

In the case that an overcoating layer is provided in the light-sensitive material of the first or second embodiment, the overcoating layer should be removed before the removing step.

In the case that an overcoating layer is provided in the light-sensitive material of the third or fourth embodiment, the overcoating layer should be removed before the laminating step.

The embodiments of the image forming method of the present invention are described below referring to the drawings.

FIG. 5 is a sectional view schematically illustrating the exposing step of the first and second embodiments of the image forming method. A latent image of silver halide (55) is formed within the exposed area (53), where the light-sensitive layer is exposed to light (51). On the other hand, silver halide (54) within the unexposed area (52) is not substantially changed.

The exposing step is described in FIG. 5 by using a multi-layered light-sensitive material shown in FIG. 3. The single-layered light-sensitive material shown in FIG. 1 can also be exposed to light in the same manner. The image forming method is further described below by using a multi-layered light-sensitive material. Of course, the single-layered light-sensitive material can also be treated in the same manner.

FIG. 6 is a sectional view schematically illustrating the developing step of the first embodiment of the image forming method. When the light-sensitive material is heated (61), a reducing agent is moved from a polymerizable layer (62 and 63) to a light-sensitive layer (64 and 65). The reducing agent develops the latent image of silver halide within the exposed area of the light-sensitive layer (65). A silver image (69) is formed from the developed silver halide, and the reducing agent is simultaneously oxidized to form an oxidation product. The oxidation product is unstable in the system of the present invention to form a radical (67). This radical is hereinafter referred to as "oxidation radical". The oxidation radical of the reducing agent (67) is moved from the exposed area of the light-sensitive layer (65) to the exposed area of the polymerizable layer (63). An ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer is hardened by the function of the radical. Thus, the hardened area (63) is formed. On the other hand, the reducing agent (66) contained in the unexposed area of the polymerizable layer and silver halide (68) contained in the light-sensitive layer are not substantially changed. Thus, the unexposed area of the polymerizable layer (62) is not hardened.

The developing step is described in FIG. 6 by using a heat development process. The developing step can also be conducted by a wet development process using a developing solution. Further, the developing step is described in FIG. 6 by using a system wherein the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer is hardened within the exposed area. The other system wherein the compound or/and the polymer is hardened within the unexposed area is also available by changing the conditions such as the kind of the reducing agent. The details are described at the item of [Reducing agent].

FIG. 7 is a sectional view schematically illustrating the transferring step of the first embodiment of the image forming method. FIG. 7 shows an image receiving material (71) and a light-sensitive material (72) just after the image is transferred. The light-sensitive material (72) is placed in contact with the image receiving material (71). Thus, the color image (74) formed on the unhardened area is transferred from the light-sensitive material to the image receiving material. The hardened area (73) remains on the light-sensitive material (72).

The transferring step described in FIG. 7 is the first embodiment wherein the unhardened area is transferred to the image receiving material. The hardened area can also be transferred according to the second embodiment by changing the conditions of the transferring step such as the amount and nature of the polymerizable compound or cross-linkable polymer, pressure and temperature. The details are described at the item of [Transferring step].

An image is formed on the image receiving material according to the above-mentioned steps. The steps are then repeated using a light-sensitive material having another color to form a two-color image on the image receiving material. The steps may be further repeated with respect to the other colors to form a full color image on the image receiving material.

The steps can be repeated by using other image receiving materials. Then, the images formed on the image receiving materials are transferred to a further (secondary) image receiving material to form a multicolor image.

FIG. 8 is a sectional view schematically illustrating the color image obtained by the repeating step of the first embodiment of the image forming method. In the image shown in FIG. 8, the steps are repeated four times using four light-sensitive materials each having a yellow (Y), magenta (M), cyan (C) or black (B) color. Thus a full color image is formed on the image receiving material (81). Black is expressed within the area (82) to which Y, M, C and B are transferred. Red is expressed within the area (83) to which Y and M are transferred. Green is expressed within the area (84) to which Y and C are transferred. Yellow is expressed within the area (85) to which Y is transferred. Blue is expressed within the area (86) to which M and C are transferred. Magenta is expressed within the area (87) to which M is transferred. Cyan is expressed within the area (88) to which C is transferred. White is expressed within the area (89) to which nothing is transferred.

As is described in FIG. 5 to FIG. 8, the first embodiment of the invention comprises the steps of:

(1) imagewise exposing to light the light-sensitive polymerizable layer (the exposing step shown in FIG. 5);

(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (the developing step shown in FIG. 6);

(3) placing the light-sensitive material in contact with an image receiving material to transfer the unhardened area to the image receiving material whereby a color image is formed on the image receiving material (the transferring step shown in FIG. 7); and then

(4) repeating the steps (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (the repeating step shown in FIG. 8).

Further, the second embodiment of the invention comprises the steps of:

(1) imagewise exposing to light the light-sensitive polymerizable layer (the exposing step shown in FIG. 5);

(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (the developing step shown in FIG. 6);

(3) placing the light-sensitive material in contact with an image receiving material to transfer the hardened area to the image receiving material whereby a color image is formed on the image receiving material (the transferring step); and then

(4) repeating the steps (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (the repeating step).

In the first order, the laminating step (A) is first conducted. In the second order, the exposing step (1) is first conducted. The first order is preferred to the second, since the first order has an advantage of very easy adjustment and operation with respect to the setting of an image.

FIG. 9 is a sectional view schematically illustrating the laminating step of the third and fourth embodiments of the image forming method. A light-sensitive material comprising a light-sensitive polymerizable layer (92) provided on a support (93) is laminated on an image receiving material (91).

The laminating step is described in FIG. 9 by using a single-layered light-sensitive material shown in FIG. 1. The multi-layered light-sensitive material shown in FIG. 4 can also be laminated on the image receiving material in the same manner. The image forming method is further described below by using a multi-layered light-sensitive material. Of course, the single-layered light-sensitive material can also be treated in the same manner.

FIG. 10 is a sectional view schematically illustrating the exposing step of the third and fourth embodiments of the image forming method. A latent image of silver halide (105) is formed within the exposed area (103), where the light-sensitive polymerizable layer is exposed to light (101). On the other hand, silver halide (104) within the unexposed area (102) is not substantially changed.

In FIG. 9 and FIG. 10, the laminating step (FIG. 9) is conducted before the exposing step (FIG. 10). The laminating step can also be conducted after the exposing step.

FIG. 11 is a sectional view schematically illustrating the developing step of the third and fourth embodiments of the image forming method. When the light-sensitive material is heated (111), a reducing agent develops the latent image of silver halide within the exposed area of the light-sensitive polymerizable layer (113). A silver image (117) is formed from the developed silver halide, and the reducing agent is simultaneously oxidized to form an oxidation radical (115). An ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer is hardened by the function of the radical. Thus, the hardened area (113) is formed. On the other hand, the reducing agent (114) and silver halide (116) contained in the light-sensitive polymerizable layer are not substantially changed. Thus, the unexposed area of the light-sensitive polymerizable layer (112) is not hardened.

The developing step is described in FIG. 11 by using a heat development process. The developing step can also be conducted by a wet development process using a developing solution. Further, the developing step is described in FIG. 11 by using a system wherein the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer is hardened within the exposed area. The other system wherein the compound or/and the polymer is hardened within the unexposed area is also available by changing the conditions such as the kind of the reducing agent.

FIG. 12 is a sectional view schematically illustrating the transferring step of the third embodiment of the image forming method. FIG. 12 shows an image receiving material (121) and a light-sensitive material (122) just after the image is transferred. The light-sensitive material (122) is placed in contact with the image receiving material (121). Thus, the color image (124) formed on the unhardened area is transferred from the light-sensitive material to the image receiving material. The hardened area (123) remains on the light-sensitive material (122).

The transferring step described in FIG. 12 is the third embodiment wherein the unhardened area is transferred to the image receiving material. The hardened area can also be transferred according to the fourth embodiment by changing the conditions of the transferring step such as the amount and nature of the polymerizable compound or cross-linkable polymer, pressure and temperature.

An image is formed on the image receiving material according to the above-mentioned steps. The steps are then repeated using a light-sensitive material having another color to form a two-color image on the image receiving material. The steps may be further repeated with respect to the other colors to form a full color image on the image receiving material.

The steps can be repeated by using other image receiving materials. Then, the images formed on the image receiving materials are transferred to a further (secondary) image receiving material to form a multicolor image.

As is described in FIG. 9 to FIG. 12, the third embodiment of the invention comprises the steps of:

(A) laminating the light-sensitive material on the image receiving material (the laminating step shown in FIG. 9)

(1) imagewise exposing to light the light-sensitive polymerizable layer (the exposing step shown in FIG. 10);

(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (the developing step shown in FIG. 11);

(3) placing the light-sensitive material in contact with an image receiving material to transfer the unhardened area to the image receiving material whereby a color image is formed on the image receiving material (the transferring step shown in FIG. 12); and

(4) repeating the steps (A) and (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (the repeating step),

wherein the order is selected from:

(A)→(1)→(2)→(3)→(4); and

(1)→(A)→(2)→(3)→(4).

Further, the fourth embodiment of the invention comprises the steps of:

(A) laminating the light-sensitive material on the image receiving material (the laminating step shown in FIG. 9)

(1) imagewise exposing to light the light-sensitive polymerizable layer (the exposing step shown in FIG. 10);

(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (the developing step shown in FIG. 11);

(3) placing the light-sensitive material in contact with an image receiving material to transfer the hardened area to the image receiving material whereby a color image is formed on the image receiving material (the transferring step); and

(4) repeating the steps (A) and (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (the repeating step),

wherein the order is selected from:

(A)→(1)→(2)→(3)→(4); and

(1)→(A)→(2)→(3)→(4).

In the first order, the laminating step (A) is first conducted. In the second order, the exposing step (1) is first conducted. The first order is preferred to the second for the reason mentioned in the third and fourth embodiments.

The above are the representative embodiments of the image forming method. In the image forming method of the present invention, optional steps may be added to the above-described steps.

When a multi-layered light-sensitive material is used in the first and second embodiments, the light-sensitive layer and a layer provided on or above the polymerizable layer should be removed after the developing step. The layers may be peeled to be removed. Further, the layers may be dissolved in or swelled with a solvent which does not dissolve the polymerizable layer.

The single-color or multicolor image formed on the image receiving material may be further transferred to another (secondary) image receiving material.

In the present invention, the image is reversed by the transferring step. The reversed image is appropriate in the case that the final color image is formed on a transparent support. On the other hand, the final image should be an erect image in the case that the image is formed on an opaque support. The reversed image can be changed to the erect image by a reversal exposure or an additional transferring step. The relation between the reversed image and the erect image should be noted when the method further contains the above-mentioned additional transferring step.

The other optional steps may be added to the method. Examples of the optional steps include a step of removing optional layers (e.g., an intermediate layer, a backing layer), a step of dull-finishing the surface of the image receiving material on which an image has been formed, and a step of adding a matting agent to the image receiving material.

The main steps of the present invention are described below in more detail.

Exposing Step

The light-sensitive material can be imagewise exposed to light from the surface of the layers (the reverse side of the support). The material can also be imagewise exposed to light from the side of the support. Between the light source and the light-sensitive polymerizable layer (or the light-sensitive layer of a multi-layered light-sensitive material), another layer, the support or an image receiving material may intervene so long as the intervening substances are transparent not to disturb the sensitivity of the light-sensitive polymerizable layer.

Examples of the exposing methods include a reflective exposure, a contact exposure through a transparent positive and a scanning exposure. The reflective exposure uses a xenon lamp, a tungsten lamp or a fluorescent lamp as the light source. The scanning exposure uses a laser beam or a light emission diode as the light source. The present invention is characterized in that an image is formed from the light-sensitive material having a sensitivity to a scanning light. Therefore, the method of the present invention is particularly advantageous to the scanning exposure.

Examples of the laser beams include a helium-neon laser, a helium-cadmium laser, an argon ion laser, a krypton ion laser, a YAG laser, a ruby laser, a nitrogen laser, a dye laser, an excimer laser, a semiconductor (e.g., GaAs/GaAlAs, InGaAsP) laser, an alexandrite laser, a copper vapor laser and an erbium laser. A light emission diode and a liquid crystal shutter are also available as the light source of the scanning exposure. The light emission diode array and a liquid crystal shutter array, which are used as the light-source of a line printer.

The wavelength of the light corresponds to the spectral sensitivity of silver halide. Near ultraviolet, visible and near infrared regions are available. The amount of the exposure is generally determined by a sensitivity of the silver halide emulsion. The amount is usually in the range of 0.01 to 10,000 ergs/cm². At the exposing step, a latent image of silver halide is formed within the exposed area.

Developing Step

The light-sensitive material is preferably developed by heating. The developing step can be conducted simultaneously with the exposing step.

The exposed light-sensitive material can be directly or indirectly heated by the known heating means. The heat development can be conducted by placing the light-sensitive material in contact with a heated material (e.g., heated plate roller), heating the light-sensitive material by a radiation heat of an infrared rays lamp, placing the light-sensitive material in a heated zone, or passing the light-sensitive material through a heated zone. The surface of the light-sensitive material may be covered to prevent the influence of the air on the developing reaction. The heating temperature and the heating time are determined by the characteristics of the light-sensitive material. The heating temperature is preferably in the range of 70° to 200° C. The heating time is preferably in the range of 1 to 180 seconds.

The light-sensitive material can also be developed by a wet development process using a developing solution. In the third and fourth embodiments of the present invention, the developing solution (preferably a condensed solution) can be coated between the light-sensitive material and the image-receiving material.

At the developing step, the latent image of silver halide is developed, and an oxidation product of the reducing agent is formed within the exposed area. In the case that the oxidation product has a function of accelerating a polymerization reaction, an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer is hardened within the exposed area. In the case that the oxidation product has a function of inhibiting a polymerization reaction, an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer is hardened within the unexposed area.

In the system wherein the unexposed area is hardened, a thermal polymerization initiator or a photopolymerization initiator is preferably contained in the light-sensitive material. When the photopolymerization initiator is used, the light-sensitive material is uniformly exposed to light after the developing step.

Transferring Step

At the transferring step of the first and second embodiments, the surface of the imagewise hardened light-sensitive material is placed in contact with an image receiving material to transfer the color image to the image receiving material. The transferring step is conducted by pressure or/and heat. The temperature is preferably in the range of 10° to 200° C., and the pressure is preferably in the range of 0 to 2,000 kg/cm².

After the developing step, the light-sensitive polymerizable layer (the polymerizable layer of the multi-layered light-sensitive material) is hardened within the exposed area or, in the alternative, within the unexposed area. As a result, the adhesion between the layer and the support is changed. When an image receiving material is placed in contact with the light-sensitive material, the hardened area, or in the alternative, the unhardened area is attached to the image receiving material. Whether the hardened area or the unhardened area is attached to the image receiving material is determined by (a) the adhesion between the unhardened area and the support, (b) the adhesion between the unhardened area and the image receiving material, (c) the adhesion between the hardened area and the support and (d) the adhesion between the hardened area and the image receiving material. The hardened area is transferred to the image receiving material under conditions that (a)>(b) and (c)<(d). On the other hand, the unhardened area is transferred to the image receiving material under conditions that (a)<(b) and (c)>(d). These conditions are determined by the nature and amount of the polymerizable compound, the nature of the binder of the light-sensitive polymerizable layer and the nature and mount of the other components. The conditions are also determined by the circumstances of the transferring step (e.g., temperature, time, pressure, humidity). Thus a color image is formed on the image receiving material.

The image receiving material can be made of an art paper, a coated paper, a printing paper and or a plastic sheet. A resin binder, a plasticizer, a surfactant or a matting agent may be coated on the paper or the sheet.

At the transferring step of the third and fourth embodiments, the image receiving material is peeled from the light-sensitive material to transfer the color image to the image receiving material. It is the same as the above-described first and second embodiments whether the unhardened area (the third embodiment) or the hardened area (the fourth embodiment) is transferred.

Laminating Step

At the laminating step of the third and fourth embodiments, the light-sensitive material is laminated on an image receiving material.

The laminating step is conducted by pressure or/and heat. For example, the light-sensitive material is placed in contact with the image receiving material, and then passed through rubber rollers to form lamination. The other known laminating methods are also available.

The image receiving material used at the laminating step preferably has a thickness in the range of 5 to 50 μm. whereby the toner image is transferred to the image receiving material. The image receiving material can be made of an art paper, a coated paper, a printing paper and or a plastic sheet. A resin binder, a plasticizer, a surfactant or a matting agent may be coated on the paper or the sheet.

In preparation of the light-sensitive material, the light-sensitive material may be laminated on the image receiving material. The embodiment using a previously prepared lamination is also included in the scope of the present invention.

The components and the elements of the light-sensitive material used in the image forming method of the present invention are described below in more detail.

Silver Halide

Silver halide is silver chloride, silver bromide, silver iodide, silver chlorobromide, silver chloroiodide, silver iodobromide or silver chloroiodobromide in the form of grains.

Various crystal forms of silver halide grains are available. Examples of the grains include a regular crystal form such as hexahedron, octahedron or tetradecahedron, an irregular form such as spherical form or tubular form, a form having crystalline defect such as a twinning plane, and a mixed form thereof.

The silver halide grains may be extremely small grains having a grain diameter (diameter of projected area) of less than 0.01 μm, or may be relatively large grains having a diameter of more 10 μm. The silver halide emulsion may be a polydispersed emulsion or a monodispersed emulsion. The monodispersed emulsion is described in U.S. Pat. No. 3,574,628 and No. 3,655,394 and U.K. Patent No. 1,413,748.

A tubular silver halide emulsion having an aspect ratio of not less than 5 is also available. The tubular silver halide grains can be easily prepared by processes described in Gutoff, "Photographic Science and Engineering, Vol. 14, pp. 248-257 (1970)", U.S. Pat. No. 4,434,226, No. 4,414,310, No. 4,433,048 and No. 4,439,520, and U.K. Patent No. 2,112,157.

With respect to the crystal structure of the silver halide grains, the individual grains may have a homogeneous halogen composition or a heterogeneous halogen composition in which the composition varies from the outer surface portion to the inside portion. The grains may have a multi-layered structure. Further, the silver halide grains may be bonded with other silver halide grains having different halogen composition through epitaxial bonding. The grains may be bonded with compounds other than the silver halide such as silver rhodanate and lead oxide.

Various substances in the form of salt can be added to the silver halide according to a conventional process at the grain formation or after the grain formation. Examples of the substances include copper, thallium, lead, cadmium, zinc, a chalcogen such as sulfur, selenium and tellurium, gold, and a group III noble metal such as rhodium, iridium, iron, platinum and palladium. The conventional process is described in U.S. Pat. No. 1,195,432, No. 1,191,933, No. 2,448,060, No. 2,628,167, No. 2,950,972, No. 3,488,709, No. 3,737,313, No. 3,772,031, No. 4,269,927 and "Research Disclosure" (RD), No. 13,452 (June, 1975).

In the case that the light-sensitive material is exposed to light in a short time and at a high illumination, iridium ion is preferably added to the silver halide in an amount of 10⁻⁸ to 10⁻³ mole, and more preferably in an amount of 10⁻⁷ to 10⁻⁵ mole based on 1 mole of silver halide.

Two or more kinds of silver halide grains which differ in halogen composition, crystal habit, grain size, and/or other features from each other can be used in combination.

The silver halide is preferably used in the form of an emulsion. The silver halide emulsion can be prepared by a known process, which is described in "Research Disclosure" (RD), No. 17,643, pp. 22-23 (Dec. 1978), (Emulsion preparation and types); and "Research Disclosure", No. 18,716, p. 648, (Nov. 1979).

The silver halide emulsion is generally used after subjecting it to physical ripening, chemical ripening and spectral sensitization. Various additives are used in those stages. The additives are described in "Research Disclosure", No. 17,643 and No. 18,716. The chemical sensitizing agent is described in No. 17,643 (p. 23) and No. 18,716 (p. 648, right side) . The spectral sensitizing agent is described in No. 17,643 (pp. 23-24) and No. 18,716 (p. 648, right side). The supersensitizing agent is described in No. 18,716 (p. 649, right side). Other additives are also described in "Research Disclosure". For example, a sensitivity-increasing agent is described in No. 18,716 (p. 648, right side), and an anti-fogging agent and a stabilizer are described in No. 17,643 (pp. 24-25) and No. 18,716 (p. 649, right side), respectively.

It is preferred to use silver halide grains having a relatively low fogging value.

The silver halide emulsion usually is a negative type. A reversal silver halide emulsion which directly forms a positive image is also available.

Reducing Agent

The reducing agent has a function of reducing the silver halide and/or a function of accelerating (or inhibiting) polymerization of the polymerizable compound or the cross-linkable polymer. There are known various reducing agents having the these functions. Examples of the reducing agents include hydroquinones, catechols, p-aminophenols, p-phenylenediamines, 3-pyrazolidones, 3-aminopyrazoles, 4-amino-5-pyrazolones, 5-aminouracils, 4,5-dihydroxy-6-aminopyrimidines, reductones, aminoreductones, o- or p-sulfonamidophenols, o- or p-sulfonamidonaphthols, 2,4-disulfonamidephenols, 2,4-disulfonamidenaphthols, o- or pacylaminophenols, 2-sulfonamidoindanones, 4-sulfonamido-5-pyrazolones, 3-sulfonamidoindoles, sulfonamidopyrazolobenzimidazoles, sulfonamidopyrazolotriazoles, α-sulfonamidoketones and hydrazines.

By adjusting the kind or amount of the above reducing agent, the polymerizable compound can be polymerized within the area where a latent image of the silver halide has been formed or, in the alternative, within the area where a latent image of the silver halide has not been formed. For example, the following system (A), (B) or (C) may be employed.

(A) When the reducing agent develops silver halide, the reducing agent itself is oxidized to form an oxidation product. The oxidation product is decomposed in the layer to form a radical. Thus a polymerization reaction proceeds within the area where the latent image of silver halide has been formed. In this system, hydrazines are used as the reducing agent singly or in combination with other reducing agent.

(B) In the case that the oxidation product has a function of inhibiting the polymerization, the polymerization is inhibited within the area where the latent image of silver halide has been formed. The polymerization is caused by a polymerization initiator within the area where the latent image of silver halide has not been formed. In this system, 1-phenyl-3-pyrazolidones are preferably used as the reducing agent.

(C) In the case that the reducing agent itself has a function of inhibiting the polymerization and the oxidation product has no or weak inhibiting function, the polymerization is inhibited within the area where the latent image of silver halide has not been formed. The polymerization is caused by a polymerization initiator within the area where the latent image of silver halide has been formed. In this system, hydroquinones are preferably used as the reducing agent.

In the systems (B) and (C), a polymerization initiator (a thermal polymerization initiator or a photopolymerization initiator) is contained in a layer of the light-sensitive material. The systems (B) and (C) are described in U.S. Pat. No. 4,649,098 and European Patent Publication No. 0202490.

The reducing agents (including compounds referred to as developing agent or hydrazine derivative) are described in Japanese Patent Provisional Publications 61(1986)-183640, No. 61(1986)-183535, No. 61(1986)-228441, No. 62(1987)-70836, No. 61(1987)-86354, No. 62(1987)-86355, No. 62(1987)-206540, No. 62(1987)-264041, No. 62(1987)-109437 and No. 63(1988)-254442, and Japanese Patent Applications No. 63(1988)-97379, No. 63(1988)-296774, No. 63(1988)-296775, No. 1(1989)-27175, No. 1(1989)-54101 and No. 1(1989)-91162. The reducing agents are also described in T. James, "The Theory of the Photographic Process", 4th edition, pp. 291-334 (1977) "Research Disclosure", Vol 170, No. 17029, pp. 9-15 (June 1978), and "Research Disclosure", Vol. 176, No. 17643, pp. 22-31 (December 1978). Further, there can be also employed a reducing agent precursor capable of releasing a reducing agent under heating or in contact with a base. Also in the light-sensitive material, various reducing agents and reducing agent precursors described in the above publications, applications and literatures can be effectively used. Thus, "the reducing agent" in the present specification means to include all the reducing agents and reducing agent precursors described in the above publications.

When the reducing agent is basic, that is, it forms a salt with an acid, the reducing agent can be used in the form of a salt with an acid. The reducing agents can be used singly or in combination. In the case that two or more reducing agents are used in combination, certain interactions between those reducing agents may be expected. One of the interactions is for an acceleration of reduction of silver halide (and/or an organic silver salt) through so-called superadditivity. The other interaction is for a chain reaction in which an oxidant of one reducing agent formed by a reduction of silver halide (and/or an organic silver salt) induced or inhibits the polymerization of the polymerizable compound by oxidation-reduction reaction with other reducing agent. Both interactions may occur simultaneously. Thus, it is difficult to determine which of the interactions has occurred in practical use.

The reducing agent is used in an amount of 0.1 to 10 mole, more preferably 0.5 to 5 mole based on 1 mole of silver halide.

Examples of the reducing agents are described below. ##STR1##

Polymerizable Compound and Cross-Linkable Polymer

The polymerizable compound used in the present invention has an ethylenic unsaturated group.

Examples of the compounds having an ethylenic unsaturated group include acrylic acids, salts of acrylic acids, acrylic esters, acrylamides, methacrylic acids, salts of methacrylic acids, methacrylic esters, methacrylamides, maleic anhydride, maleic esters, itaconic esters, styrenes, vinyl ethers, vinyl esters, N-vinyl heterocyclic compounds, allyl ethers, allyl esters, and derivatives thereof.

Acrylic esters and methacrylic esters are preferred.

Examples of the acrylic esters include n-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, benzyl acrylate, furfuryl acrylate, ethoxyethoxyethyl acrylate, tricyclodecanyloxy acrylate, nonylphenyloxyethyl acrylate, 1,3-dioxolane acrylate, hexanediol diacrylate, butanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, tricyclodecanedimethylol diacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexacrylate, diacrylate of polyoxyethylenated bisphenol A, 2-(2-hydroxy-1,1-dimethylethyl)-5-hydroxymethyl-5-ethyl-1,3-dioxanediacrylate, 2-(2-hydroxy-1,1-dimethylethyl)-5,5-dihydroxymethyl-1,3-dioxanetriacrylate, triacrylate of propylene oxide addition product of trimethylolpropane, polyacrylate of hydroxypolyether, polyester acrylate and polyurethane acrylate.

Examples of the methacrylic esters include methyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, butanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate and dimethacrylate of polyoxyalkylenated bisphenol A.

The polymerizable compound is commercially available. Examples of the commercially available compounds include Alonix M-309, M-310, M-315, M-400, M-6100, M-8030, M-8100 (trade names, all available from Toa Gosei Kagaku Kogyo Co., Ltd.) and Kayarad HX-220, HX-620, R-551, TMPTA, D-330, DPHA, DPCA-60, R604, R684 (trade names, all available from Nippon Kayaku Co., Ltd.).

The cross-linkable polymer used in the present invention has a functional group which is reactive to a radical. The polymer may be a homopolymer or a copolymer with a monomer which does not have a reactive group. Examples of the polymer include a polymer having a double bond (ethylenic or another unsaturated bond) in its molecule, a polymer having a polyoxyalkylene unit in its molecule and a polymer containing a halogen atom in its molecule. A polymer which forms a polymer radical by dehalogenatation or dehydrogenation is also available as the cross-linkable polymer. Further, two polymer radicals may be coupled with each other by a cross-linking reaction. Furthermore, a polymer may be cross-linked by a reaction with an ethylenically unsaturated polymerizable compound.

The reactive functional group is contained in the side chain or the main chain. The functional group may be introduced into the side chain by a polymeric reaction of the polymer The functional group may also be introduced into the side chain by a polymerization of monomers having the group. Examples of the repeating units of the polymer having a functional group in its side chain are shown below. ##STR2##

The other examples of the polymers include a synthetic rubber (e.g., polybutadiene, polyisoprene, styrene-isoprene copolymer, styrene-butadiene-acrylonitrile copolymer), a natural rubber, polyethylene oxide, polypropylene oxide, polyvinyl chloride (including a copolymer thereof), polyvinylidene chloride (including a copolymer thereof), polyvinyl acetate (including a copolymer thereof), chlorinated polyethylene, polyvinyl butyral, methyl cellulose, ethyl cellulose and butyl cellulose.

The cross-linkable polymer is described at pages 147 to 192 in "Polymer Reaction" (edited by Polymer Society in Japan, Kyoritsu Shuppan, 1978).

In the case that an alkaline solution is used to remove the unhardened area, the cross-linkable polymer preferably contains an acidic functional group in its molecule. Examples of the acidic functional groups include carboxyl, an acid anhydride group, phenolic hydroxyl, sulfo, sulfonamido and sulfonimido. In the case that a binder of the layer is a polymer made by an addition reaction, the cross-linkable polymer may be a copolymer of a monomer having an cross-linkable group with a monomer having an acidic group. Examples of the monomers include acrylic acid, methacrylic acid, crotonic acid, maleic acid, phthalic acid, maleic anhydride, p-carboxystyrene, p-hydroxystyrene, p-hydroxyphenylacrylamide, hydroxyethyl methacrylate, hydroxyethylmethacrylamide and p-vinylbenzenesulfonic acid.

The polymerizable compound and the cross-linkable polymer can be used singly or in combination of two or more compounds or polymers. Further, a compound formed by bonding a polymerizable functional group such as a vinyl group or a vinylidene group to chemical structure of a reducing agent or a colored substance is also used as the polymerizable compound. A light-sensitive material using a compound which serves as both a reducing agent and a polymerizable compound or both a colored substance and a polymerizable compound can be also included in the embodiments of the light-sensitive material.

The amount of the polymerizable compound and the cross-linkable polymer contained in the polymerizable layer is preferably in the range of 3 to 90% by weight, more preferably in the range of 15 to 60% by weight, based on the whole amount of the polymerizable layer.

Base and Base Precursor

The light-sensitive material may contain a base or base precursor. The base or base precursor is preferably used in the heat development process.

Various organic or inorganic bases and their precursors (e.g., decarboxylation type, thermal decomposition type, reaction type and complex salt-formation type) are available.

Inorganic bases are described in Japanese Patent Provisional Publication No. 62(1987)-209448. Examples of the organic bases include tertiary amine compounds (described in Japanese Patent Provisional Publication No. 62(1987)-170954), bisamidine compounds, trisamidine compounds or tetraamidine compounds (described in Japanese Patent Provisional Publication No. 63(1988)-316760) and bisguanidine compounds, trisguanidine compounds or tetraguanidine compounds (described in Japanese Patent Provisional Publication No. 64(1989)-68746). In the present invention, a base having a pKa value of not less 7 is preferred.

In the present invention, a base precursor is preferred to the base from the viewpoint of the storage stability of the light-sensitive material.

Preferred examples of the base precursors include salts of organic acids with bases which is decarboxylated under heating and urea compounds which release bases under heating. Examples of the reaction mechanisms of the base precursor include a reaction between the base precursor and a salt containing anion having higher compatibility with transition metal acetylide or transition metal ion than acetylide anion, and a reaction of introducing into water both of a basic metallic compound which is hardly dissolved in water and a compound capable of reacting with metal ion of the basic metallic compound in a water medium to form a complex salt so as to release a base through a reaction between those two compounds in the presence of water.

The base precursor preferably releases a base at a temperature in the range of 50° to 200° C., and more preferably in the range of 80° to 160° C.

The light-sensitive material employing a base or a base precursor is described in Japanese Patent Provisional Publication No. 62(1987)-264041. A light-sensitive material employing a tertiary amine as a base is described in Japanese Patent Provisional Publication No. 62(1987)-170954. A light-sensitive material employing dispersed grains of a hydrophobic organic base compound having a melting point of 80° to 180° C. is described in Japanese Patent Provisional Publication No. 62(1987)-209523. A light-sensitive material employing a guanidine derivative having a solubility of not more than 0.1% is described in Japanese Patent Provisional Publication No. 63(1988)-70845. A light-sensitive material employing hydroxides or salts of alkali metals or alkaline earth metals is described in Japanese Patent Provisional Publication No. 62(1987)-209448.

A light-sensitive material employing acetylide compounds as a base precursor is described in Japanese Patent Provisional Publication No. 63(1988)-24242. A light-sensitive material employing a salt of propiolic acid as a base precursor and further containing silver, copper, a silver compound or a copper compound as a catalyst of the base production reaction is described in Japanese Patent Provisional Publication No. 63(1988)-46446. A light-sensitive material containing the salts of propiolic acid under the condition of being separated from the silver, copper, silver compound or copper compound is described in Japanese Patent Provisional Publication No. 63(1988)-81338. A light-sensitive material containing free ligands in addition to the salts of propiolic acid and the silver, copper, silver compound or copper compound is described in Japanese Patent Provisional Publication No. 63(1988)-97942. A light-sensitive material employing salts of the propiolic acid as a base precursor and further containing heat fusible compounds as an accelerator of the base production reaction is described in Japanese Patent Provisional Publication No. 63(1988)-46447. A light-sensitive material employing a salt of sulfonyl acetate as a base precursor and further containing heat fusible compound as an accelerator for the base production reaction is described in Japanese Patent Provisional Publication No. 63(1988)-48453. A light-sensitive material employing compounds in which isocyanate or isothiocyanate is bonded to an organic base is described in Japanese Patent Provisional Publication No. 63(1988)-96652. A light-sensitive material containing a nucleating agent as a decomposition accelerator of the above compound is described in Japanese Patent Provisional Publication No. 63(1988)-173039.

A light-sensitive material employing as a base precursor a bisamidine or trisamidine salt of carboxylic acid capable of being decarboxylated is described in Japanese Patent Provisional Publication No. 64(1989)-9441. A light-sensitive material employing as a base precursor a bisguanidine or trisguanidine salt of carboxylic acid capable of being decarboxylated is described in Japanese Patent Provisional Publication No. 64(1989)-68749.

The base or the base precursor can be used in an amount of preferably 0.5 to 50 mole, more preferably 1 to 20 mole based on 1 mole of silver halide.

Colorant

In the present invention, a colorant is contained in the light-sensitive material.

The colorant has a function of forming a visible (to human eye) color image (e.g., a color proof). There is no specific limitation on the colorant provided that the colorant does not remarkably inhibit the hardening reaction of the polymerizable compound or the cross-linkable polymer, the sensitivity of silver halide or the developing reaction. Various known pigments and dyes are available.

The pigments are commercially available. Further, pigments are described in various publications such as "Handbook of Color Index", "New Handbook of Pigments", (Nippon Ganryo Gijutsu Kyokai (ed.), 1977), "New Applied Technique of Pigments", (CMC Publishing, 1986), and "Technique of Printing Ink", (CMC Publishing, 1984).

Examples of the pigments include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, violet pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments and polymer pigments. Concrete examples of the pigments include insoluble azo pigments, azo lake pigments, condensation azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene pigments, perynone pigments, thioindigo pigments, quinacridone pigments, dioxadine pigments, isoindolinone pigments, quinophthalone pigments, dye-type lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments and inorganic pigments.

The pigment can be per se used or can be used after being subjected to surface treatment. As the surface treatment, there can be employed a method of coating a resin or wax on the surface of the pigment, a method of depositing a surface active agent thereon, a method of bonding a reactive substance (e.g., silane coupling agent, epoxy compound and polyisocyanate) to the surface of the pigment. Those methods are described, for example, in "Nature and Application of Metal Soap", (Saiwai Shobo), "Technique of Printing Ink", (CMC Publishing, 1984), and "New Applied Technique of Pigments", (CMC Publishing, 1986).

The particle size of the pigment is preferably in the range of 0.01 to 10 μm, more preferably in the range of 0.05 to 1 μm.

The pigment can be introduced into the light-sensitive polymerizable layer (or the polymerizable layer) by adding or dispersing it into a coating solution for the formation of the layer. For dispersing the pigment in the coating solution, various dispersing techniques conventionally used for the preparation of ink or toner can be employed. As the dispersing device, there can be used a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron a three-roll mill and a press kneader. Details of the devices are described in "New Applied Technique of Pigments", (CMC Publishing, 1986).

Dyes are also available as the colorant. The dye, that is, a material being itself colored, there can be used those commercially available and those described in various publications (e.g., "Handbook of Dyes", Yuki Kagaku Kyokai (ed.), 1970). Concrete examples of the dyes include azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, quinonimine dyes and methine dyes.

The upper limit of the amount of the colorant is determined provided that the colorant does not remarkably inhibit the hardening reaction, the sensitivity of silver halide or the developing reaction. The amount is preferably so determined that the optical density of the formed image is analogous to that of the printed matter. The color density depends on the nature of each of the pigment or dye. The amount is usually in the range of 0.01 to 2 g/m², and more preferably in the range of 0.02 to 1 g/m².

Two or more colorants may be used in combination. The hue (absorption spectrum) of the colorant is preferably analogous to that of the printing ink. In the present invention, the pigment is preferred to the dye, since the printing ink usually contains a pigment.

Support

The support of the light-sensitive material is made of a chemically and thermally stable substance. The support may be transparent. Examples of the substances include polyolefins (e.g., polyethylene, polypropylene), polyvinyl halides (e.g., polyvinyl chloride, polyvinylidene chloride), cellulose derivatives (e.g., cellulose acetate, nitrocellulose, cellophane), polyamides, polystyrene, polycarbonate, polyimides and polyesters. Polyethylene terephthalate and polycarbonate (including thermally treated substances) are preferred, since they are excellent in the dimensional stability and the transparency. A biaxially stretched polyethylene terephthalate is particularly preferred. The support may be surface treated with corona discharge or ultraviolet irradiation. An undercoating layer may be provided on the support.

Binder of Polymerizable Layer

A binder may be added to the polymerizable layer of the multi-layered light-sensitive material to enhance the strength of the layer. The binder preferably does not decrease the solubility of the unhardened area of the polymerizable layer in the solvent. The binder also preferably does not increase the solubility of the hardened area in the solvent. Various natural or synthetic polymers are available as the binder. The synthetic polymer can be formed by an addition reaction (of a vinyl monomer) or a condensed reaction. Examples of the synthetic polymers include vinyl polymers (e.g., polystyrene, polyacrylate, polymethacrylate), polyesters, polyamides, polyurethanes, polyester-polyamides and copolymers thereof.

In the case that an alkaline solution is used to remove the unhardened area, the binder preferably contains an acidic functional group in its molecule. Examples of the acidic functional groups include carboxyl, an acid anhydride group, phenolic hydroxyl, sulfo, sulfonamido and sulfonimido. In the case that the binder is a polymer made by an addition reaction, the binder may be a copolymer of a monomer having an cross-linkable group with a monomer having an acidic group. Examples of the monomers include acrylic acid, methacrylic acid, crotonic acid, maleic acid, phthalic acid, maleic anhydride, p-carboxystyrene, p-hydroxystyrene, p-hydroxyphenylacrylamide, hydroxyethyl methacrylate, hydroxyethylmethacrylamide and p-vinylbenzenesulfonic acid.

There is not specific limitation on the amount of the binder so long as the binder does not inhibit the hardening reaction in the polymerizable layer. The amount is usually in the range of 0 to 80% by weight, and preferably in the range of 0 to 70% by weight, based on the whole amount of the polymerizable layer.

Polymerization Inhibitor

A polymerization inhibitor may be added to the polymerizable layer to prevent the dark reaction. Various known polymerization inhibitors are available. Examples of the polymerization inhibitors include a nitrosamine, a thiourea, a thioamide, a urea compound, a phenol derivative, a nitrobenzene derivative and an amine. Concrete examples include A1 salt of cupferron, N-nitrosodiphenylamine, allylthiourea, an aryl phosphate, p-toluidine, φ-toluquinone, nitrobenzene, pyridine, phenathiazine, β-naphthol, naphthylamine, t-butylcatechol, phenothiazine, chloranil, p-methoxyphenol, pyrogallol, hydroquinone and an alkyl or aryl-substituted hydroquinone.

Organic Metallic Salt

An organic metallic salt can be added to the light-sensitive layer containing silver halide. The organic metallic salt relates to an oxidation-reduction reaction at the heat development wherein the latent image of silver halide functions as the catalyst. It is considered that the organic metallic salt has a function of accelerating the oxidation-reduction reaction. The organic silver salt is described in Japanese Patent Provisional Publications No. 59(1984)-55429 and No. 62(1987)-3246.

The metal of the organic salt preferably silver. The organic moiety of the salt preferably is an aliphatic carboxylic acid, an aromatic carboxylic acid, a thiocarbonyl compound having a mercapto group or α-hydrogen, an acetylene compound and an imino compound.

Examples of the aliphatic carboxylic acids include acetic acid, butyric acid, succinic acid, sebacic acid, adipic acid, oleic acid, linoleic acid, linolenic acid, tartaric acid, palmitic acid, stearic acid, behenic acid and camphoric acid. When the number of the carbon atoms is small, the formed silver salt is unstable. Therefore, the carboxylic acid should contain a relatively large number of the carbon atoms.

Examples of the aromatic carboxylic acids include benzoic acid derivatives, quinolinic acid derivatives, naphthoic acid derivatives, salicylic acid derivatives, gallic acid, tannic acid, phthalic acid, phenylacetic acid derivatives and pyromellitic acid.

Examples of the thiocarbonyl compounds include 3-mercapto-4-phenyl-1,2,4-triazole, 2-mercaptobenzimidazole, 2-mercapto-5-aminothiadiazole, 2-mercaptobenzothiazole, s-alkylthioglycolic acid (the number of the carbon atoms in the alkyl group is in the range of 12 to 22), dithiocarboxylic acids (e.g., dithioacetic acid), thioamides (e.g., thiostearamide), 5-carboxy-1-methyl-2-phenyl-4-thopyridine, mercaptotriazine, 2-mercaptobenzoxazole and 3-amino-5-benzylthio-1,2,4-triazole. The mercapto compounds described in U.S. Pat. No. 4,123,274 are also available.

Examples of the imino compounds include benzotriazole and derivatives thereof, 1,2,4-triazole, 1H-tetrazole, carbazole, saccharin, imidazole and derivatives thereof. Examples of the benzotriazole derivatives include alkyl-substituted benzotriazoles (e.g., methylbenzotriazole), halogen-substituted benzotriazoles (e.g., 5-chlorobenzotriazole), carboimidobenzotriazoles (e.g., butylcarboimidobenzotriazole), nitrobenzotriazoles, sulfobenzotriazoles, carboxybenzotriazoles and salts thereof and hydroxybenzotriazoles. U.S. Pat. No. 4,220,709 describes 1,2,4-triazole and 1H-tetrazole.

A similar effect can be obtained in the case that the organic moiety of the organic metallic salt in place of the salt itself is added to the light-sensitive layer. Two or more organic metallic salts can be used in combination.

The organic silver salt is generally used in an amount of 0 to 10 moles, preferably 0 to 1 mole based on 1 mole of silver halide. The total amount of the silver halide and the organic silver salt contained in the light-sensitive layer is preferably in the range of 1 mg/m² to 5 g/m², more preferably in the range of 10 mg/m² to 0.5 g/m² in terms of silver.

Binder of the Light-Sensitive Layer

A hydrophilic binder is preferably contained in the light-sensitive layer.

The hydrophilic binder has a hydrophilic group or a hydrophilic bond in its molecule. Examples of the hydrophilic group include carboxyl, hydroxyl (including alcohol and phenol), sulfo, sulfonamido, sulfonimido and amido. Examples of the hydrophilic bond include urethane bond, ether bond and amido bond.

The hydrophilic binder preferably is soluble in water or swells in water. The polymer which swells in water has an affinity to water, but is not soluble in water because of the cross-linking structure of the polymer.

The natural or synthetic polymers can be used as the hydrophilic binder. Examples of the natural hydrophilic polymer include polysaccharide such as starch derivatives, cellulose derivatives, alginic acid, pectic acid, gum arabic and pullulan, and protein such as casein and gelatin. The denatured polymers are also available. In preparation of the light-sensitive material (at the stage of coating or drying), these natural polymers may be denatured or cross-linked. The synthetic hydrophilic polymer is a polymer or copolymer of water-soluble monomers. The water-soluble monomers have a hydrophilic group such as carboxyl, acid anhydride, hydroxyl, sulfo (including a salt thereof), amido, amino and ether. Examples of the monomer are described in "Application and Market of Water-soluble Polymer" (CMC, p. 16-18). A copolymer formed from the above-mentioned monomers by polymerization or cross-linking (cf., copolymers described in U.S. Pat. No. 4,913,998) can also be used.

The other examples of the hydrophilic polymer include polyvinyl alcohol, polyvinyl ether, polyvinyl pyrrolidone and derivatives thereof. Polyvinyl alcohol is particularly preferred.

Polyvinyl alcohol may be denatured by copolymerization with another monomer. A copolymer of vinyl acetate and another monomer is saponified to form the denatured polyvinyl alcohol. Examples of the monomer copolymerized with the vinyl acetate include ethylene, a higher vinyl carboxylate, a higher alkyl vinyl ether, methyl methacrylate and acrylamide. Polyvinyl alcohol may also be denatured after the saponification. Hydroxyl in polyvinyl alcohol can be modified by etheration, esterification or acetylation. A cross-linked polyvinyl alcohol is also available. Examples of the cross-linking agent include aldehyde, methylol compounds, diisocyanate, divinyl compounds, dicarboxylic acids, borates, titanium and copper. The denatured or cross-linked polyvinyl alcohol is described in "Poval" 3rd ed., Kobunshi Kanko-Kai, p. 281-285 and 256-260.

The molecular weight is preferably in the range of 3,000 to 500,000. The hydrophilic polymer binder is preferably used in an amount in the range of 0.05 g to 20 g/m², and more preferably in the range of 0.1 to 10 g/m².

The light-sensitive layer preferably has a function of preventing oxygen from the air to the polymerizable layer at the heat development process. The oxygen functions as a polymerization inhibitor. Therefore, the hydrophilic polymer preferably has a low transmission coefficient of oxygen of not more than 1.0×10⁻¹¹ cm³.cm/cm².sec.cmHg.

The examples of the hydrophilic polymer binder having the low transmission coefficient of oxygen include polyvinyl alcohol and its derivatives, gelatin and copolymer of vinylidene chloride. The derivatives of polyvinyl alcohol include the above-mentioned denatured polyvinyl alcohol (formed by saponification of the block copolymer of polyvinyl acetate and another monomer). The molecular weight is preferably in the range of 3,000 to 500,000.

Polyvinyl alcohol preferably has a high saponification degree of not less than 70%, more preferably of not less than 80%, most preferably of not less than 95%. The polyvinyl alcohol having the high saponification degree has a very low transmission coefficient of oxygen.

Heat Development Accelerator

The light-sensitive material can contain a heat development accelerator. The heat development accelerator may be contained in any layers of the light-sensitive material. The function of the heat development accelerator has not yet been analyzed. There are two assumptions. According to one assumption, the heat development accelerator has a function of increasing the plasticity of a polymer (contained in the polymerizable layer or the light-sensitive layer). According to the other assumption, the accelerator has another function of accelerating the dispersion of the components in the layers when it is dissolved by heat of the development process. As a result, the reactions (decomposition of a base precursor, reduction of silver halide and a hardening reaction) at the heat development process are accelerated.

The heat development accelerator has been known as a plasticizer. The known plasticizers are described in "Plastic Additives (written in Japanese)", p. 21-63 (Taisei-sha); Plastics Additives, Second Edition; Hanser Publishers, Chapter 5, p. 251-296; Thermoplastic Additives, Marcel Dekker Inc., Chapter 9, p. 345-379; Plastic Additives, An Industrial Guide, Noyes Publications, Section 14, p. 333-485: The Technology of Solvents and Plasticizers, John Willey & Sons Inc., Chapter 15, p. 903-1027; Industrial Plasticizers, Pergamon Press; Plasticizer Technology, Vol. 1, Reinhold Publishing corp.; and Plasticization and Plasticizer Process, American Chemistry.

The heat development accelerator has also been known as a hot-melt solvent. Examples of the hot-melt solvent include polar compounds described in U.S. Pat. No. 3,347,675; 1,10-decandiol, methyl anisate and biphenyl suberate described in "Research Disclosure" pp. 26-28, (Dec. 1976); sulfonamide derivatives; polyethylene glycol derivatives; cyclic amides; aromatic compounds; esters and amides; ethers and thioethers; ketones, carbonates, sulfoxides, phosphonates; and phenols.

Preferred examples of the heat development accelerator include glycols (e.g., diethylene glycol, dipropylene glycol), polyhydric alcohols (e.g., glycerol, butanediol, hexanediol), saccharides, formates, ureas (e.g., urea, diethylurea, ethyleneurea, propyleneurea), a urea resin, a phenol resin, amides (e.g., acetamide, propionamide) and sulfonamides. Two or more heat development accelerators can be used in combination. The heat development accelerators can be added to two or more layers of the light-sensitive material.

The amount of the heat development accelerator is preferably in the range of 0 to 2 g/m², and more preferably in the range of 0 to 1 g/m².

The Other Additives

The light-sensitive material can contain the other additives such as an antifogging agent, a silver development accelerator, a development stopping agent, a surface active agent and a dispersing agent.

The antifogging agent, the silver development accelerator and the dispersing agent often have two or more functions. Accordingly, it is difficult to classify these compounds. Examples of these compounds include cyclic amides, polyethylene glycol derivatives, thiol derivatives, acetylene compounds, sulfonamide derivatives and azoles or azaindenes described in "Research Disclosure" pp. 24-25 (1978). These compounds are generally used in an amount of 10⁻⁷ to 1 mole based on 1 mole of the silver halide.

The development stopping agent can be used in the light-sensitive material to obtain a clear image constantly regardless of the temperature and time for the development process. The development stopping agents are compounds to neutralize a base or react with a base to reduce the base concentration in the layer to stop development, or compounds that mutually react with silver or a silver salt to suppress development, after the appropriate development. More specifically, examples of the development stopping agents include acid precursors capable of releasing acids upon heating, electrophilic compounds capable of undergoing substitution reaction with a coexisting base upon heating, nitrogen-containing heterocyclic compounds, mercapto compounds, and precursors thereof.

Coloring Agent

A coloring agent can be added to the light-sensitive material as an antihalation agent. Various pigments and dyes are available as the coloring agent provided that the agent does not inhibit the hardening reaction of the polymerizable layer and the sensitivity or the developing reaction of silver halide. Where the coloring agent is used as the antihalation agent, the color of the agent should absorb the light used in the exposing step. Examples of the coloring agent are the same as those of the colorant.

The coloring agent can also be contained in the light-sensitive layer or an adjacent layer thereof as an antiirradiation dye. The antiirradiation dye is described in U.S. Pat. No. 3,697,037, No. 3,423,207, No. 2,865,752, U.K. Patents No. 1,030,392 and No. 1,100,546.

The amount of the coloring agent is determined provided that the colorant does not remarkably inhibit the hardening reaction, the sensitivity of silver halide or the developing reaction. The amount is usually in the range of 0.01 to 2 g/m², and more preferably in the range of 0.02 to 1 g/m².

In the present invention, the coloring agent may disturb the hue of the colorant contained in the polymerizable layer. Therefore, the coloring agent is preferably not used in the polymerizable layer, or the amount is preferably as small as possible.

The coloring agent can be contained in an optional layer such as a backing layer, an intermediate layer. The coloring agent may also be contained in two or more layers. Two or more coloring agents can be used in combination.

Polymerization Initiator

In the systems (B) and (C) described at the item of [Reducing agent], a thermal polymerization initiator or a photopolymerization initiator is contained in the light-sensitive material. Various known thermal polymerization initiators and photopolymerization initiators are available. When the photopolymerization initiator is used, the light-sensitive material is uniformly exposed to light after the developing step.

A thermal polymerization initiator is described in "Addition Polymerization and Ring Opening Polymerization", pp. 6-18, edited by the Editorial Committee of High Polymer Experimental Study of the High Polymer Institute, published by Kyoritsu Shuppan (1983). Examples of the thermal polymerization initiators include azo compounds such as azobisisobutyronitrile, 1,1'-azobis(1-cyclohexanecarbonitrile), dimethyl-2,2'-azobisisobutyrate, 2,2'-azobis(2-methylbutyronitrile) and azobisdimethylbaleronitrile; organic peroxides such as benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, t-butyl hydroperoxide and cumene hydroperoxide; inorganic peroxides such as hydrogen peroxide, potassium persulfate and ammonium persulfate; and sodium p-toluenesulfinic acid.

The photopolymerization initiator is described in Oster et al., Chemical Review, vol. 68, p. 125-151 (1968) and Kosar, Light-Sensitive System, p. 158-193, John Willey & Sons (1965). Examples of the photopolymerization initiator include carbonyl compounds (e.g., α-alkoxyphenyl ketones, polycyclic quinones, benzophenone derivatives, xanthones, thioxanthones and benzoines), halogen-containing compounds (e.g., chlorosulfonyl or chloromethyl polynuclear aromatic compounds, chlorosulfonyl or chloromethyl heterocyclic compounds, chlorosulfonyl or chloromethyl benzophenones and fluorenones), haloalkanes, α-halo-α-phenylacetophenones, redox couples of photo-reducible dye and reducing agent, organic sulfur compounds, peroxides, photo semi-conductors (e.g., titanium dioxide and zinc oxide), metallic compounds (e.g., ferrous salt, metallic salt of carbonyl compound, metal complex and uranyl salt), silver halide, azo compounds and diazo compounds.

Concrete examples of the photopolymerization initiators include 2-dimethoxy-2-phenylacetophenone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone, benzoin butyl ether, benzoinisopropyl ether, benzophenone, Michler's ketone, 4,4-diethylaminobenzophenone, chloromethylbenzophenone, chlorosulfonylbenzophenone, 9,10-anthraquinone, 2-methyl-9,10-anthraquinone, chlorosulfonyl anthraquinone, chloromethyl anthraquinone, 9,10-phenanthrenequinone, xanthone, chloroxanthone, thioxanthone, chlorothioxanthone, 2,4-diethylthioxanthone, chlorosulfonylthioxanthone, chloromethylbenzothiazole, chlorosulfonylbenzoxazole, chloromethylquinoline, fluorene and carbon tetrabromide.

Examples of the photo-reducible dyes include methylene blue, thionine, rose bengal, erythrocin-β, eosine, rhodamine, phloxin-β, safranine, acryflavine, riboflavine, fluorescein, uranine, benzoflavine, acryzine orange, acryzine yellow and benzanthrone.

Examples of the reducing agents (hydrogen donative compounds) employable with these dyes include β-diketones (e.g., dimedone and acetylacetone), amines (e.g., triethanolamine, diethanolamine, monoethanolamine, diethylamine and triethylamine), sulfinic acids (e.g., p-toluenesulfinic acid and benzenesulfinic acid), salts of those sulfinic acids, N-phenylgrycine, L-ascorbic acid and salts thereof, thiourea, and allylthiourea.

A molar ratio between the photo-reducible dye and the reducing agent is preferably in the range of 1:0.1 to 1:10.

Also preferably employable as the photopolymerization initiators are commercially available ones such as Irgacure-651™ and Irgacure-907™ (produced by Ciba-Geigy).

The polymerization initiator is used in an amount of preferably 0.001 to 0.5 g, and more preferably 0.01 to 0.2 g based on 1 g of the polymerizable compound.

Optional Layers

Optional layers may be added to the single-layered or multi-layered light-sensitive materials. An overcoating layer (or a cover film layer) has a function of protecting the surface of the light-sensitive material or a function of preventing oxygen in the air from inhibiting the polymerization reaction. A backing layer may function as an antihalation layer. The backing layer may also function of preventing adhesion between two light-sensitive materials when they are stocked. An intermediate layer may also function as an antihalation layer. The backing layer may also function of adjusting adhesion between two layers. A layer containing a matting agent may be provided on the surface facing an image receiving material. The matting agent has a function of contacting tightly the light-sensitive material with the image receiving material to prevent bubble formed between the materials. Various known matting agents are available. The matting agent may also be contained in the image receiving material.

An overcoating layer can be prepared by coating a solution of a polymer on a light-sensitive material. The overcoating layer can also be prepared by laminating a polymer film on the light-sensitive material. The overcoating layer may be formed by the lamination just before the image forming method. The hydrophilic binders described at the item of [Binder of the light-sensitive layer] are available as the polymer of the overcoating layer. Polyvinyl alcohols are particularly preferred. The polyvinyl alcohol preferably has a high saponification degree of not less than 85%, and more preferably of not less than 95%. The polyvinyl alcohol having the high saponification degree has a very low transmission coefficient of oxygen. The overcoating layer also functions as a protective layer. The overcoating layer may be peeled from the light-sensitive material just before the laminating step. Two or more overcoating layers may be provided on the light-sensitive material.

The present invention is further described by the following examples without limiting the invention.

EXAMPLE 1 Preparation of Light-Sensitive Material for Yellow Image Formation

A light-sensitive material for yellow image formation (multi-layered light-sensitive material) was prepared in the following manner.

Preparation of Support

The following dye was added to a gelatin solution to prepare a coating solution of a backing layer. The coating solution was coated on a biaxially stretched polyethylene terephthalate film having the thickness of 100 μm. The amount of gelatin contained in the backing layer was 3.9 g/m². The absorbance of the backing layer was 0.9 at 488 nm. On the surface (the reverse of the backing layer) of the polyethylene terephthalate film, 10 wt. % isopropyl alcohol solution of shellac was coated and dried to form an undercoating layer having the thickness of 0.3 μm. Thus prepared film having the backing and undercoating layers was used as the support. ##STR3##

Preparation of Yellow Pigment Dispersion

The following composition was dispersed at 2,000 rpm for 2 hours using a Dynomill to obtain a yellow pigment dispersion having the average particle size of 0.25 μm.

    ______________________________________                                         Yellow pigment dispersion   Amount                                             ______________________________________                                         Following yellow pigment (C.I.: Pigment Yellow 14)                                                         30.0 g                                             Allyl methacrylate/methacrylic acid copolymer                                                              50.0 g                                             (copolymerization ratio = 80/20)                                               Propylene glycol monomethyl ether                                                                          320.0 g                                            ______________________________________                                          (Yellow pigment)                                                               ##STR4##                                                                 

Formation of Polymerizable Layer

The following coating solution was coated and dried on the support to form a polymerizable layer having the thickness of 1.3 μm.

    ______________________________________                                         Coating solution of polymerizable layer                                                                    Amount                                             ______________________________________                                         Dipentaerythritol hexaacrylate                                                                             10.0 g                                             Allyl methacrylate/methacrylic acid copolymer                                                               1.0 g                                             (copolymerization ratio = 80/20)                                               Yellow pigment dispersion   40.0 g                                             Reducing agent (J)           1.0 g                                             Methyl ethyl ketone         30.0 g                                             ______________________________________                                    

Preparation of Silver Halide Emulsion

Gelatin, potassium bromide and water were placed in a vessel and kept at 55° C. An appropriate amount of ammonium was added to the vessel. Further, an aqueous solution of silver nitrate and an aqueous solution of potassium bromide containing hexachloroiridate (III) (the molar ratio of iridium to silver is 10⁻⁷ mole) were added to the vessel according to a double jet method while keeping the pAg of 7.60 in the reaction vessel. Potassium iodide was then added to the mixture to prepare a monodispersed silver iodobromide emulsion having the average grain size of 0.25 μm (content of silver iodide: 0.2 mole %). In the emulsion, 98% of the silver halide grains are within the range of ±40% of the average grain size. The emulsion was desalted, and adjusted to pH 6.2 and pAg 8.6. The emulsion was then subjected to gold and sulfur sensitization using sodium thiosulfate and chloroauric acid. Further, 200 ml of methanol solution of the following sensitizing dye (concentration: 2.0M/l) was added to 1 kg of the emulsion. The mixture was stirred for 15 minutes at 60° C. to prepare a silver halide emulsion. ##STR5##

Preparation of Base Precursor Dispersion

In 750 g of 3 wt. % aqueous solution of poll/vinyl alcohol was dispersed 250 g of powder of the following base precursor using Dynomill dispersing device. The particle size of the base precursor was about not more than 0.5 μm. ##STR6##

Formation of Light-Sensitive Layer

The following coating solution was coated and dried on the polymerizable layer to form a light-sensitive layer having the dry thickness of about 4.0 μm.

    ______________________________________                                         Coating solution of light-sensitive layer                                                                  Amount                                             ______________________________________                                         10 Wt. % aqueous solution of polyvinyl alcohol having                                                      13.2   g                                           the saponification degree of 88% (PVA-205 produced                             by Kuraray Co., Ltd.)                                                          Base precursor dispersion   1.24   g                                           Ethyleneurea                0.40   g                                           0.13 Wt. % methanol solution of the following                                                              0.54   g                                           additive (1)                                                                   0.22 Wt. % methanol solution of the following                                                              0.54   g                                           additive (2)                                                                   Silver halide emulsion      0.37   g                                           The following light absorbing agent                                                                        60     mg                                          5 Wt. % aqueous solution of the following surface                                                          1.8    g                                           active agent                                                                   Water                       1.9    g                                           ______________________________________                                          (Additive (1))                                                                 ##STR7##                                                                       (Additive (2))                                                                 ##STR8##                                                                      ?                                                                               (Light absorbing agent)                                                        ##STR9##                                                                      ?                                                                               (Surface active agent)                                                         ##STR10##                                                                     ?                                                                         

Formation of Overcoating Layer

With 100 g of 10 wt. % aqueous solution of polyvinyl alcohol having the saponification degree of 98.5% (PVA-117 produced by Kuraray Co., Ltd.) was mixed 4 g of 5 wt. % aqueous solution of the surface active agent to prepare a coating solution. The coating solution was coated and dried on the light-sensitive layer to form an overcoating layer having the dry thickness of about 3.0 μm.

Preparation of Light-Sensitive Material for Magenta Image Formation

A light-sensitive material for magenta image formation (multi-layered light-sensitive material) was prepared in the same manner as in the preparation of the material for yellow image formation except that the following magenta pigment was used. ##STR11##

Preparation of Light-Sensitive Material for Cyan Image Formation

A light-sensitive material for cyan image formation (multi-layered light-sensitive material) was prepared in the same manner as in the preparation of the material for yellow image formation except that the following cyan pigment was used. ##STR12##

Preparation of Light-Sensitive Material for Black Image Formation

A light-sensitive material for black image formation (multi-layered light-sensitive material) was prepared in the same manner as in the preparation of the material for yellow image formation except that carbon black (C.I.: Pigment Black 7) was used in the black pigment.

Preparation of Image Receiving Material

The following coating solutions A and B were coated and dried on a polyethylene terephthalate film (thickness: 100 μm) to form layers A and B having the dry thicknesses of 20 μm and 1.5 μm respectively. Thus an image receiving material was prepared.

    ______________________________________                                                                   Amount                                               ______________________________________                                         Coating solution A                                                             Ethylene/vinyl acetate copolymer (copolymerization                                                         15     g                                           weight ratio = 81/19)                                                          Chlorinated polyethylene    0.075  g                                           Fluorinated surface active agent (Florade FC-430                                                           0.26   g                                           produced by 3M)                                                                Matting agent               0.1    g                                           (inside: polymethyl methacrylate having a melting                              point of 80 to 125° C.;                                                 outside: methyl methacrylate/acrylic acid/di-                                  vinylbenzene copolymer having a melting point of                               0 to -25° C. (weight ratio = 98.5/3/0.5);                               weight ratio of inside/outside: 7/3;                                           particle size: 20 μm)                                                       Toluene                     100    ml                                          Coating solution B                                                             Polyvinyl butyral           4      g                                           Fluorinated surface active agent (Florade FC-430                                                           0.05   g                                           produced by 3M)                                                                Methanol                    50     ml                                          Methyl ethyl ketone         20     ml                                          Methyl cellosolve acetate   20     ml                                          ______________________________________                                    

Formation of Color Proof

A color proof was formed using the above-prepared multi-layered light-sensitive materials according to the first embodiment of the present invention.

The light-sensitive material for yellow image formation was imagewise (for yellow image) exposed to light of 488 nm by a scanning exposure (light source: air cooling argon ion laser). The surface exposure was 10 μJ/cm². The light-sensitive material was heated for 40 seconds from the backing layer on a hot plate at 130° C. The light-sensitive material was then immersed in warmed water to remove the light-sensitive layer and the overcoating layer. Thus the developed polymerizable layer was exposed. The light-sensitive material having the yellow image was placed in contact with the image receiving material, and passed through rubber rollers at about 80° C. to transfer the yellow image of the unhardened area from the light-sensitive material to the image receiving material. Thus an yellow image was formed on the image receiving material.

A magenta image was formed on the light-sensitive material in the same manner as in the formation of the yellow image. Then, the magenta image was transferred to another image receiving material.

A cyan image was also formed on the light-sensitive material in the same manner as in the formation of the yellow image. Then, the cyan image was transferred to another image receiving material.

A black image was further formed on the light-sensitive material in the same manner as in the formation of the yellow image. Then, the black image was transferred to another image receiving material.

The image receiving material to which the yellow image had been transferred was placed in contact with an art paper (final image receiving material) and heated at about 100° C. to transfer the yellow image to the final image receiving material. The magenta image was then transferred to the final image receiving material to which the yellow image had been transferred. The cyan image and the black image were transferred to the final image receiving material in the same manner to form a color proof on the final image receiving material. The image quality of the color proof was excellent, and the digital image data were fully reproduced in the color proof.

EXAMPLE 2 Preparation of Light-Sensitive Material for Yellow Image Formation

A single-layered light-sensitive material for yellow image formation was prepared in the following manner.

Preparation of Support

A support was prepared in the same manner as in Example 1.

Formation of Light-Sensitive Polymerizable Layer

In 10 g of trimethylolpropane triacrylate was dissolved 0.6 g of the reducing agent (J) used in Example 1. The solution was mixed with 5 g of the yellow pigment dispersion used in Example 1 to obtain an oily solution. With 50 g of 10 wt. % aqueous solution of polyvinyl alcohol (PVA-40 produced by Kuraray Co., Ltd.) was mixed 1 g of 5 wt. % aqueous solution of the surface active agent used in Example 1 to form an aqueous solution. The oily solution was added to the aqueous solution, and the mixture was stirred using a homogenizer to obtain an O/W emulsion of the polymerizable compound.

The following coating solution was coated and dried on the support to form a light-sensitive polymerizable layer having the dry thickness of about 5 μm.

    ______________________________________                                         Coating solution of the light-sensitive                                        polymerizable layer         Amount                                             ______________________________________                                         The O/W emulsion of the polymerizable compound                                                             10.0 g                                             The base precursor dispersion used in Example 1                                                            1.2 g                                              Sorbitol                    0.4 g                                              0.22 Wt. % methanol solution of the additive (2) used                                                      0.5 g                                              in Example 1                                                                   The silver halide emulsion used in Example 1                                                               0.37 g                                             Water                       7.5 g                                              ______________________________________                                    

Preparation of Light-Sensitive Material for Magenta Image Formation

A single-layered light-sensitive material for magenta image formation was prepared in the same manner as in the preparation of the material for yellow image formation except that the magenta pigment shown in Example 1 was used.

Preparation of Light-Sensitive Material for Cyan Image Formation

A single-layered light-sensitive material for cyan image formation was prepared in the same manner as in the preparation of the material for yellow image formation except that the cyan pigment shown in Example 1 was used.

Preparation of Light-Sensitive Material for Black Image Formation

A single-layered light-sensitive material for black image formation was prepared in the same manner as in the preparation of the material for yellow image formation except that carbon black (C.I.: Pigment Black 7) was used as the black pigment.

Formation of Color Proof

A color proof was formed using the above-prepared single-layered light-sensitive materials according to the first embodiment of the present invention.

The light-sensitive material for yellow image formation was imagewise (for yellow image) exposed to light of 488 nm by a scanning exposure (light source: air cooling argon ion laser). The surface exposure was 3 μJ/cm². The light-sensitive material was heated for 30 seconds on a hot plate having a Teflon surface membrane at 130° C. The surface of the developed light-sensitive polymerizable layer was placed in contact with the image receiving material used in Example 1, and passed through rubber rollers at about 80° C. to transfer the yellow image of the unhardened area from the light-sensitive material to the image receiving material. Thus an yellow image was formed on the image receiving material.

A magenta image was formed on the light-sensitive material in the same manner as in the formation of the yellow image. Then, the magenta image was transferred to the image receiving material to which the yellow image had been transferred.

A cyan image was also formed on the light-sensitive material in the same manner as in the formation of the yellow image. Then, the cyan image was transferred to the image receiving material.

A black image was further formed on the light-sensitive material in the same manner as in the formation of the yellow image. Then, the black image was transferred to the image receiving material. Thus a full color image was formed on the image receiving material.

The image receiving material was placed in contact with an art paper (final image receiving material) and passed through rubber rollers at 100° C. to transfer the full color image to the final image receiving material to form a color proof on the final image receiving material. The image quality of the color proof was excellent, and the digital image data were fully reproduced in the color proof.

EXAMPLE 3 Preparation of Light-Sensitive Material

A single-layered light-sensitive materials for yellow, magenta, cyan and black color image formations were prepared in the same manner as in Example 2, except that a polyethylene terephthalate film was used as the support.

Formation of Color Proof

A color proof was formed using the above-prepared single-layered light-sensitive materials according to the third embodiment of the present invention.

The light-sensitive material for the yellow image formation was placed in contact with the image receiving material used in Example 1, and then passed through rubber rollers at about 100° C. to form a lamination.

The lamination was imagewise (for yellow image) exposed to light of 488 nm from the side of the the transparent support of the light-sensitive material by a scanning exposure (light source: air cooling argon ion laser). The surface exposure was 10 μJ/cm². The lamination was heated for 30 seconds on a hot plate at 130° C. The image receiving material was peeled from the lamination. The unhardened area of the light-sensitive polymerizable layer was transferred to the image receiving material to form a yellow image on the image receiving material. The hardened area remains on the light-sensitive material.

The light-sensitive material for magenta image formation was laminated on the image receiving material, in which the yellow image had been formed. The lamination was processed in the same manner as in the formation of the yellow image.

The light-sensitive material for cyan image formation was laminated on the image receiving material, and the lamination was processed in the same manner as in the formation of the yellow image.

The light-sensitive material for black image formation was laminated on the image receiving material, and the lamination was processed in the same manner as in the formation of the yellow image.

Thus a color proof was formed on the image receiving material. The image quality of the color proof was excellent, and the digital image data were fully reproduced in the color proof. 

We claim:
 1. An image forming method comprising the steps of (A), (1), (2), (3) and (4):(A) laminating on an image receiving material a light-sensitive material, which comprises a support, a light-sensitive layer and a polymerizable layer in this order, said light-sensitive layer containing silver halide, said polymerizable layer containing an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer and a colorant, and a reducing agent being contained in the light-sensitive layer or the polymerizable layer; (1) imagewise exposing to light the light-sensitive layer; (2) heating the layers at a temperature in the range of 70° to 200° C. for 1 to 180 seconds to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area; (3) peeling the image receiving material from the light-sensitive material to transfer the unhardened area to the image receiving material whereby a color image is formed on the image receiving material; and (4) repeating the steps (A) and (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material, wherein (A) is prior to (2), (1) is prior to (2), and (2) is prior to (3).
 2. An image forming method comprising the steps of (A), (1), (2), (3) and (4):(A) laminating on an image receiving material a light-sensitive material, which comprises a support, a light-sensitive layer and a polymerizable layer in this order, said light-sensitive layer containing silver halide, said polymerizable layer containing an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer and a colorant, and a reducing agent being contained in the light-sensitive layer or the polymerizable layer; (1) imagewise exposing to light the light-sensitive layer; (2) heating the layers at a temperature in the range of 70° to 200° C. for 1 to 180 seconds to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area; (3) peeling the image receiving material from the light-sensitive material to transfer the unhardened area to the image receiving material whereby a color image is formed on the image receiving material; and (4) repeating the steps (A) and (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material, wherein (A) is prior to (2), (1) is prior to (2), and (2) is prior to (3). 